[media] videobuf: Allow reqbufs(0) to free current buffers

All the infrastructure for this is already there, and despite our desires for
the old videobuf code to go away, it is currently still in use in 18 drivers.

Allowing reqbufs(0) makes these drivers behave consistent with modern drivers,
making live easier for userspace, see e.g. :
https://bugzilla.gnome.org/show_bug.cgi?id=735660

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

diff --git a/drivers/media/v4l2-core/videobuf-core.c b/drivers/media/v4l2-core/videobuf-core.c
index fb5ee5dd8fe933cbdd371aeecf41a3047d2e0e39..b91a266d0b7efcced9ad3bbca2b08cb398377505 100644 (file)
--- a/drivers/media/v4l2-core/videobuf-core.c
+++ b/drivers/media/v4l2-core/videobuf-core.c
@@ -441,11 +441,6 @@ int videobuf_reqbufs(struct videobuf_queue *q,
        unsigned int size, count;
        int retval;
 
-       if (req->count < 1) {
-               dprintk(1, "reqbufs: count invalid (%d)\n", req->count);
-               return -EINVAL;
-       }
-
        if (req->memory != V4L2_MEMORY_MMAP     &&
            req->memory != V4L2_MEMORY_USERPTR  &&
            req->memory != V4L2_MEMORY_OVERLAY) {
@@ -471,6 +466,12 @@ int videobuf_reqbufs(struct videobuf_queue *q,
                goto done;
        }
 
+       if (req->count == 0) {
+               dprintk(1, "reqbufs: count invalid (%d)\n", req->count);
+               retval = __videobuf_free(q);
+               goto done;
+       }
+
        count = req->count;
        if (count > VIDEO_MAX_FRAME)
                count = VIDEO_MAX_FRAME;